In various industries, items are sold in batches satisfying various constraints. As an example, items of non-uniform size, shape or weight, e.g. food items such as meat, fish, fruit and vegetables, are typically handled and delivered to customers in batches having a substantially uniform size, shape and weight. Typically, a batch of items must fulfill requirements defined by a contract between a delivering and a receiving part, and most often, minimum weight of the batch is a key issue. Normally, the part of the batch that exceeds the minimum weight is considered by the delivering part as a loss and is often referred to as “giveaway”, overweight or “overpack”.
Typically, batches are formed by weighing the items individually, e.g. as they are moved by a conveyer system across a dynamic scale. In a computer system, the weight of each item is compared with weights of a plurality of receptacles, e.g. bins wherein batches are formed. Often, the computer system uses statistical algorithms for assigning specific items to specific bins under consideration of required minimum weight of the batch and a desire not to produce batches with more overweight, i.e. giveaway, than required under the present conditions, i.e. given the weights of the items and the required minimum weight of the batches.
Evidently, there is a correlation between the amount of giveaway, the required minimum weight of the batches, and the weight distribution of the items being batched. In general, the larger the items are and the smaller the batches are, the more giveaway is expected.
U.S. Pat. No. 6,388,209 discloses a method to automatically and accurately portion a sequential flow of items by weight. The method uses a pool of individual items of known weight to select from in order to perform batches.
WO2003008917 discloses a method using two flows of items to create batches. One flow is used for coarse filling up of the batches while the other flow of items, “fine flow”, is used to fill up the batches. The fine flow consists of a sequence of n-items. The weight of the items is registered by a weighing means and stored. Information from the weight distribution of the n-items is then used to accurately batch to a final batch weight with minimum overweight.
Existing systems for batching items, e.g. conveyor systems for continuous batching of food items, are sometimes provided with a computer system, which is capable of registering certain process parameters, e.g. the batching throughput, e.g. determined in weight units or determined in numbers of pieces per time unit.
GB2116732 entitled “Distributing bodies of different weight to units of predetermined weight”, discloses a method and apparatus for batching items. Attempts to solve this problem using information from dynamic weighing system to batch items based thereon.
It is, however, very difficult even for skilled operators to evaluate the performance of the system. As an example, an operator may be satisfied by knowing that a large number of batches are formed within a certain time unit, while he never realizes that the amount of giveaway or the amount of batches with underweight is large, and even if control weighing of the batches reveals the truth, the complex nature of the batching process makes it difficult to determine the reason for the large number of batches with overweight or underweight, neither to say if the situation is better or worse than expected.
One reason for an undesirable result could be that the weight distribution of the items is not suitable for the batch or pack size being processed and another reason could be that a scale is out of order. In the existing systems for batching, it is therefore difficult to optimize the batching process, e.g. with the objective to minimize giveaway.
The present invention provides a tool to aid in the optimization of the batching process.